# Publications

## Towards simulating star formation in turbulent high-z galaxies with mechanical supernova feedback

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY **451** (2015) 2900-2921

## Simplified models for dark matter searches at the LHC

Physics of the Dark Universe **9-10** (2015) 8-23

© 2015. This document <sup>a</sup>59Summary of the discussions and conclusions following from Dark Matter @ LHC 2014, held at Merton College, Oxford, on September 25-27, 2014. outlines a set of simplified models for dark matter and its interactions with Standard Model particles. It is intended to summarize the main characteristics that these simplified models have when applied to dark matter searches at the LHC, and to provide a number of useful expressions for reference. The list of models includes both s-channel and t-channel scenarios. For s-channel, spin-0 and spin-1 mediations are discussed, and also realizations where the Higgs particle provides a portal between the dark and visible sectors. The guiding principles underpinning the proposed simplified models are spelled out, and some suggestions for implementation are presented.

## Measurement of the Atmospheric nu(e) Spectrum with IceCube

PHYSICAL REVIEW D **91** (2015) ARTN 122004

## Translational symmetry of high order tokamak flux surface shaping in gyrokinetics

ArXiv (2015)

A particular translational symmetry of the local nonlinear $\delta f$ gyrokinetic model is demonstrated analytically and verified numerically. This symmetry shows that poloidally translating all the flux surface shaping effects with large poloidal mode number by a single tilt angle has an exponentially small effect on the transport properties of a tokamak. This is shown using a generalization of the Miller local equilibrium model to specify an arbitrary flux surface geometry. With this geometry specification we find that, when performing an expansion in large flux surface shaping mode number, the governing equations of gyrokinetics are symmetric in the poloidal translation of the high order shaping effects. This allows us to take the fluxes from a single configuration and calculate the fluxes in any configuration that can be produced by translating the large mode number shaping effects. This creates a distinction between tokamaks with mirror symmetric flux surfaces and tokamaks without mirror symmetry, which is expected to have important consequences for generating toroidal rotation using up-down asymmetry.

## Turbulent momentum transport due to neoclassical flows

ArXiv (2015)

Intrinsic toroidal rotation in a tokamak can be driven by turbulent momentum transport due to neoclassical flow effects breaking a symmetry of turbulence. In this paper we categorize the contributions due to neoclassical effects to the turbulent momentum transport, and evaluate each contribution using gyrokinetic simulations. We find that the relative importance of each contribution changes with collisionality. For low collisionality, the dominant contributions come from neoclassical particle and parallel flows. For moderate collisionality, there are non- negligible contributions due to neoclassical poloidal electric field and poloidal gradients of density and temperature, which are not important for low collisionality.

## Galaxy merger histories and the role of merging in driving star formation at z > 1

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY **452** (2015) 2845-2850

## A detailed study of feedback from a massive star

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY **448** (2015) 3248-3264

## Observation of finite-wavelength screening in high-energy-density matter.

Nature communications **6** (2015) 6839-

A key component for the description of charged particle systems is the screening of the Coulomb interaction between charge carriers. First investigated in the 1920s by Debye and Hückel for electrolytes, charge screening is important for determining the structural and transport properties of matter as diverse as astrophysical and laboratory plasmas, nuclear matter such as quark-gluon plasmas, electrons in solids, planetary cores and charged macromolecules. For systems with negligible dynamics, screening is still mostly described using a Debye-Hückel-type approach. Here, we report the novel observation of a significant departure from the Debye-Hückel-type model in high-energy-density matter by probing laser-driven, shock-compressed plastic with high-energy X-rays. We use spectrally resolved X-ray scattering in a geometry that enables direct investigation of the screening cloud, and demonstrate that the observed elastic scattering amplitude is only well described within a more general approach.

## Black hole evolution - I. Supernova-regulated black hole growth

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY **452** (2015) 1502-1518

## Gas flow in barred potentials

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY **449** (2015) 2421-2435

## Developed turbulence and nonlinear amplification of magnetic fields in laboratory and astrophysical plasmas.

Proceedings of the National Academy of Sciences of the United States of America **112** (2015) 8211-8215

The visible matter in the universe is turbulent and magnetized. Turbulence in galaxy clusters is produced by mergers and by jets of the central galaxies and believed responsible for the amplification of magnetic fields. We report on experiments looking at the collision of two laser-produced plasma clouds, mimicking, in the laboratory, a cluster merger event. By measuring the spectrum of the density fluctuations, we infer developed, Kolmogorov-like turbulence. From spectral line broadening, we estimate a level of turbulence consistent with turbulent heating balancing radiative cooling, as it likely does in galaxy clusters. We show that the magnetic field is amplified by turbulent motions, reaching a nonlinear regime that is a precursor to turbulent dynamo. Thus, our experiment provides a promising platform for understanding the structure of turbulence and the amplification of magnetic fields in the universe.

## Identification of globular cluster stars in RAVE data - I. Application to stellar parameter calibration

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY **451** (2015) 1229-1246

## Gaia-ESO Survey: Analysis of pre-main sequence stellar spectra

ASTRONOMY & ASTROPHYSICS **576** (2015) ARTN A80

## SELF-GRAVITY, RESONANCES AND ORBITAL DIFFUSION IN STELLAR DISKS

ASTROPHYSICAL JOURNAL **806** (2015) ARTN 117

## On the interpretation of dark matter self-interactions in Abell 3827

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY **452** (2015) L54-L58

## INTERMITTENCY AND ALIGNMENT IN STRONG RMHD TURBULENCE

ASTROPHYSICAL JOURNAL **807** (2015) ARTN 39

## Editorial Special issue: Macroscopic randomness in astrophysical plasmas: The legacy and vision of Ya. B. Zeldovich

JOURNAL OF PLASMA PHYSICS **81** (2015) ARTN 391810403

## Flow damping in stellarators close to quasisymmetry

PLASMA PHYSICS AND CONTROLLED FUSION **57** (2015) ARTN 014014

## Fluctuation-dissipation relations for a plasma-kinetic Langevin equation

Journal of Plasma Physics **81** (2015)

© 2014 Cambridge University Press. A linearised kinetic equation describing electrostatic perturbations of a Maxwellian equilibrium in a weakly collisional plasma forced by a random source is considered. The problem is treated as a kinetic analogue of the Langevin equation and the corresponding fluctuation-dissipation relations are derived. The kinetic fluctuation-dissipation relation reduces to the standard fluid one in the regime where the Landau damping rate is small and the system has no real frequency; in this case the simplest possible Landau-fluid closure of the kinetic equation coincides with the standard Langevin equation. Phase mixing of density fluctuations and emergence of fine scales in velocity space is diagnosed as a constant flux of free energy in Hermite space; the fluctuation-dissipation relations for the perturbations of the distribution function are derived, in the form of a universal expression for the Hermite spectrum of the free energy. Finite-collisionality effects are included. This work is aimed at establishing the simplest fluctuation-dissipation relations for a kinetic plasma, clarifying the connection between Landau and Hermite-space formalisms, and setting a benchmark case for a study of phase mixing in turbulent plasmas.